This proposal seeks to study the human EEG by means of a frequency and phase indicating toposcope. This is radically different from conventional recording methods and from other map-like presentations of brain electrical activity. It is capable of detecting very small frequency and phase changes. The recordings will be correlated with a relatively stable physiological variable (menstrual cycle) to determine if serial relationships occur. The study is small and the statistical method rudimentary, although proof against any placebo effects. The objective is a validation of the unique method of data presentation, rather than a study of physiologic phenomena per se.